The Observation of Humoral Responses after Influenza Vaccination in Patients with Rheumatoid Arthritis Treated with Japanese Oriental (Kampo) Medicine: An Observational Study

Objective. The efficacy of influenza vaccination in patients treated with Japanese Oriental (Kampo) Medicine is unknown. The objectives of this study were to observe the efficacy of influenza vaccination in RA patients treated with Kampo. Methods. Trivalent influenza subunit vaccine was administered to 45 RA patients who had received Kampo. They were divided into 2 groups: RA patients treated without MTX (“without MTX group”) and treated with MTX (“with MTX group”). Antibody titers were measured before and 4 weeks after vaccination using hemagglutination inhibition assay. Results. Geometric mean titers (GMTs) of anti-influenza antibodies significantly increased for all influenza strains. Response to the influenza vaccination in RA patients treated with Kampo was not lower than that of healthy subjects and the response in the “with MTX group” had a tendency to be higher than that in RA patients treated with MTX in the previous study. There was no significant difference in the GMT after 4 weeks between the “with MTX group” and the “without MTX group.” A decreased efficacy in both seroprotection and seroconversion was not found in the “with MTX group.” Conclusion. These observations may open the way for further clinical trials to establish the efficacy for the influenza vaccination in RA patients treated with Kampo.